CVE-2019-14842

libnbd: remote code execution vulnerability

Published Nov 26, 2019 CVSS 3.1 · 9.8 Critical EPSS 1.8% KEV · Not listed
Description
Structured reply is a feature of the newstyle NBD protocol allowing the server to send a reply in chunks. A bounds check which was supposed to test for chunk offsets smaller than the beginning of the request did not work because of signed/unsigned confusion. If one of these chunks contains a negative offset then data under control of the server is written to memory before the read buffer supplied by the client. If the read buffer is located on the stack then this allows the stack return address from nbd_pread() to be trivially modified, allowing arbitrary code execution under the control of the server. If the buffer is located on the heap then other memory objects before the buffer can be overwritten, which again would usually lead to arbitrary code execution.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
EUVD EUVD EUVD-2019-5966 Structured reply is a feature of the newstyle NBD protocol allowing the server to send a reply in chunks. A bounds check which was supposed to test for chunk offsets smaller than the beginning of the request did not work because of signed/unsigned confusion. If one of these chunks contains a negative offset then data under control of the server is written to memory before the read buffer supplied by the client. If the read buffer is located on the stack then this allows the stack return address from nbd_pread() to be trivially modified, allowing arbitrary code execution under the control of the server. If the buffer is located on the heap then other memory objects before the buffer can be overwritten, which again would usually lead to arbitrary code execution.
Weaknesses

Sources

Status
PUBLISHED
Assigner
redhat
Published
Updated
Aug 5, 2024, 12:26 AM
Reserved
Aug 10, 2019, 12:00 AM
Status
Modified
Published
Nov 26, 2019, 4:15 PM
Modified
Jun 17, 2026, 2:19 AM
Severity
Moderate
Public date
Oct 9, 2019, 12:00 AM